1. Field of the Invention
The present invention relates to a device for varying the position of a main lens in a copying machine in order to change the copying magnification.
2. Description of the Prior Art
In a conventional magnification changing device for a copying machine, a carriage supporting a main lens is moved on guide rails by a lead screw or a ball screw, and the carriage is stopped at a predetermined magnification position by a limiter or the like. However, it is difficult to stop the carriage accurately at a set position with such a screw, and the stop position is always inaccurate due to backlash.
In addition, the screw produces a loud noise when it starts or stops rotating, and the optical system may be adversely affected by the impact which is caused when the screw stops. Thus, the conventional magnification changing device has many disadvantages.